1. avatar donkeymagician
    I got a cornford roadhouse amp about 3 months ago and when i play on the lower (a and e) strings theres an annoying rattle. I think its loose valves. I pushed them in nice and snug and it stopped the noise for a while, but now its back. Do I need new valves?? I was thinking of changing them anyway. What would be a good replacement set??

    3 x ECC83/12AX7 preamp valves, 2 x EL34 power valves

    thats what i need. Groove tubes?? Also. Its ok to just pull out the old ones and push in the new ones...isnt it??
  2. avatar Sadoldgit
    sounds like microphonic valves - this usually affects just the preamp valves, and you can replace those simply and cheaply without needing to rebias.

    If it persists, your power amp valves may be dying.

    Look for -

    misting of the glass [vacuum gone]
    cracks in glass [often if amp moved when hot]
    plates glowing red hot in one valve when amp on [and I mean more than the usual glow you get in use]

    if you need to replace poweramp valves, then the amp needs to be rebiased - a potentially dangerous job.


    new valves here -

    http://www.watfordvalves.com/


    and

    http://hotroxuk.com
  3. avatar heartsanddrums
    I'd say it's probably the output valves. In my experience they're the most likely cause of this kind of rattle, though it's less common with EL34s than with EL84s. Play a note that induces the rattle, then lightly (and carefully!) press upwards on the output valves. If the noise stops, you've found the problem. A new pair of valves will probably help.

    The amp will need to be re-biased so you might need to take it to someone who can do this for you, depending on how difficult it is or how comfortable you are doing it yourself.
  4. avatar donkeymagician
    i think that is the problem, cos as i explained, when i pushed it in it stopped. Do you have any idea which valves would be best?? Im going for high gain and clarity. Maybe electro harmonix??
  5. avatar oxo
    Bairds stock most of the groove tube range.02890 351358 8)
  6. avatar Sadoldgit
    JJ`s are hard to beat TBH.

    Buy a selection of ecc83`s and experiment with them - pretty cheap to do and can yield great results.

    Dont believe the hype re expensive power tubes .
    Get a matched set, but most of the fancy EH and GT tubes are made by Sovtek, just rebranded by the Americans.
  7. avatar Lap Dog Shuffle
    [quote:c7fc030ba3="Sadoldgit"]Get a matched set, but most of the fancy EH and GT tubes are made by Sovtek, just rebranded by the Americans.[/quote:c7fc030ba3]Isn't there something else a bit weird going on? New Sensor (manufacturer of EH and GT) gets its tubes where it can, so if the country of manufacture is marked as Slovakia on EH or GT branded tubes then they are essentially re-branded JJs!?

    Exactly why you're better off buying JJs, you know what you're getting.
  8. avatar Setzer
    As mentioned previously JJ's would probably be your best bet if you are looking clarity.

    Other ones can be a bit fizzy for instance Tungsol but they have their uses too eg if your technique isnt the best they will hide a certain amount of "loose" playing.

    You can get a set of high gain JJ's which probably would be perfect for what you want.

    Have you considered mixing the tube makes? I put a Mullard CV4024 in my V1 slot and it transfomed my amp,beautiful clear chiming cleans and smooth defined gain for lead work.

    There is so much to learn about tubes but it really boils down to personal preference and trial and error.But if you want something decent not costly and a good place to start go with the JJ's.I have them in mine and they are superb.

    As for power amp tubes the only ones I would ever use are winged "C" Svetlanas.
  9. avatar Recycled Alien
    I doubt if new valves will be a solution if it's vibration of the glass body of the valves.

    You can buy spring clips which grip the valves into the sockets.

    Or maybe there's a fault in the socket itself, and you'd need someone to replace it. Simple job, but you'd want it to be done by somebody you could trust to know what they're doing.
  10. avatar Cugel
    [quote:c3cca4cce3="Recycled Alien"]I doubt if new valves will be a solution if it's vibration of the glass body of the valves.
    [/quote:c3cca4cce3]

    Innards can loosen in valves - particularly in combos. Gives a glassy tinkling sound through the speakers. I replaced the power valves in the Carvin I just sold for this very reason. Three out of the four had gone rattly. You can pin-point the specific valve(s) by switching the amp on and taking it off stand-by and then going round the back and gently flicking the valves one by one with your middle or ring finger. If the valve is dodgy, you will get the aforementioned tinkling sound through the speakers. Affected valves should be replaced. Power valves should be replaced in sets.

    John
  11. avatar Recycled Alien
    [quote:3ffdb2604e="Cugel"][quote:3ffdb2604e="Recycled Alien"]I doubt if new valves will be a solution if it's vibration of the glass body of the valves.
    [/quote:3ffdb2604e]

    Innards can loosen in valves - particularly in combos. Gives a glassy tinkling sound through the speakers.[/quote:3ffdb2604e]Ah, right. I didnt think of that.
  12. avatar donkeymagician
    Yeah, all sounds like good info. Think ill try replacing them. Was just off the phone to cornford and they werent much help. Ive only had the amp a few months but apparently valves arent covered in the warranty :evil: Guess Ill have to pay myself for the new ones. The JJ's sound good, where would i get a set and how do i go about getting a matched set? Do I just order 3 of the same ones?? What EL84s should I match with the JJ 12AX7's??
  13. avatar donkeymagician
    hey, i just did turned the amp on on when it warmed up i tapped the valves with a pen. The all made a normal pen-on-glass, but slightly amplified thru the speaker noise, bar one of the power valves, which made a loud clunking noise when i tapped it, much more so than the other one. Can I assume this is the problem??
  14. avatar Cugel
    Sounds like you've found a dodgy valve!

    Get the amp revalved.
  15. avatar Sadoldgit
  16. avatar scumbag
    do a search here for tony hamilton , he is an amp tech who lives in dundonald, ive had him modify my hand wired cornford head and he comes very well recommended indeed.
  17. avatar Setzer
    If you are wanting to put Electro Harmonix EL34's and JJ 12AX7's in your amp I have 3 JJ's and I have 2 EH EL34's that I dont need at the minute.

    The JJ's are brand new only put into my amp to check if they were working and the EL34's have only an hour or so of use on them.

    If your interested make me an offer,I was keeping them for spares so if you dont want them no probs either way.
  18. avatar iwkil
    My first post!
    BTW Donkey, How do you like the Roadhouse 30, other than the obvious, I have a Harlequin (love it) and was thinking of upgrading to the Roadhouse Combo 30, is yours the Combo of Head/Cab?

    Cheers Rob
  19. avatar donkeymagician
    hey, its great. I wouldnt call it an upgrade cos its not handwired like the other cornford stuff, but still sounds great. I just upgraded the valves (obviously) and went with JJ's that i ordered from Matamp and it sounds even better...smoother breakup and more balanced frquency reange. Really love and would highly reccommend this amp. If were gigging anytime soon (bar the one in dublin :-D) you could come try it if you want. Think were playing in lurgan early nov